How to use Mysql Date function in doctrine dql zend framework

Question

I need mysql date function in order by as I only want to sort with date not dateTime.

 $dql  = "SELECT r FROM Entities\Reservation r ";
 $dql .= "JOIN r.lot l ";
 $dql .= "LEFT JOIN r.car c";
 $dql .= " WHERE l.id = '" . $lot->id . "'" ;
 $dql .= " AND r.complete ='1' ";
 $dql .= " AND r.cancelled=0";
 $dql .= " ORDER BY r.start DESC, c.is_disabled_person DESC";        

 $query = $this->getEntityManager()->createQuery($dql);
 $query = $this->getResult();